Rain island effect in Shenzhen City

Data on precipitation, temperature, impervious surface with long series and high resolution were used to study rain island effect in Shenzhen City．Impact of urbanization on air temperature, precipitation in Shenzhen City from 1979-2017 was characterized．Mann-Kendall trend test Sen’s slope estimator, Pettitt test, and Pearson correlation analysis were used to analyze extreme climate indices．Impervious surface was found to have increased from 58.24 km² (2.92%) in 1985 to 932.4 km² (46.68%) in 2017．Urbanization was found concentrated mainly in the western urban area．Urbanization was found to have significant impact on temperature．Extreme temperature indices in the western urban area were found to have increased significantly compared with the eastern suburbs．The indices showed significant positive correlation with impervious surface. Shenzhen City showed a limited rain island effect, and the spatial distribution was similar to urban heat island．The total number of precipitations under 9 hours was found to have increased, number of precipitations of over 10 hours decreased, but precipitation intensity increased．Extreme precipitation indices in western urban area were found to have increased compared with the eastern suburbs, showing significant positive correlation with impervious surface．Precipitation center in Shenzhen City has tended to shift to the western urban area．